ISSN:
1432-2048
Keywords:
Hordeum
;
Lysine
;
Metabolic control
;
Methionine
;
Threonine
;
Triticum
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Excised wheat (Triticum aestivum L. var. Maris Freeman) and barley (Hordeum vulgare L. var. Maris Mink) embryos were grown on medium containing both nitrate and ammonium ions. Addition of lysine (1 mM) plus threonine (1 mM) caused a synergistic inhibition of growth measured by length of first leaf or dry weight. The inhibition was specifically relieved by methionine, homocysteine and homoserine. Threonine at 0.2–0.3 mM caused half-maximal inhibition of growth at all lysine concentrations whereas lysine increased the synergistic inhibition up to 3 mM. The inhibition is explained by a model in which lysine acts as a feedback inhibitor of aspartate kinase and threonine of homoserine dehydrogenase. This is compatible with published studies of the enzymes involved. The implications of these findings for using lysine plus threonine as a selection system for lysine-overproducing cereals are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00387135
